The S10 T5 will have 1352xxxx cast into the case in a number of places. This will identify it as a BW T5 but will tell you nothing about the internals. (ie; gear and OD ratio) Likewise, the Camaro T5 will have casting numbers in the case of 1351 or 1352. My WC Camaro T5 mech speedo, has a case number of 1351 while the upc tag carries the numbers 1352 xxxxxxxxx.
This isn't going to tell you much with the exception that if your case does not carry a 1351 or 1352 you don't have a T5.
A couple of ways to verify a 5 speed transmission: it should have 6 distinct shift positions...1st -5th and then reverse, or turn the input shaft 360 degrees while in 4th gear....should be 1:1....if you think you have the 5th position (all the way to the right and forward)....turn the OUTPUT shaft 1 full turn and the INPUT shaft should rotate less than 270 degrees for a .63/.72 OD while a .86 OD will turn past 270 degrees with the shifter in 5th gear position.
Dave
